The inducible transcription factor Nuclear Factor-kappa B (NF-xcexaB) participates in the regulation of multiple cellular genes, including many involved in the immune and inflammatory processes (for example, GM-CSF, IL-6, IL-8 and IL-2). NF-xcexaB is a member of the rel family of protein complexes, and is activated by cellular exposure to various factors, including phorbol 12-myristate 13-acetate (PMA), lipopolysaccharide (LPS), interleukin-1 (IL-1), tumor necrosis alpha (TNFxcex1), and ultraviolet radiation. See Baldwin, Annu. Rev. Immunol. 14:649 (1996). NF-xcexaB has also been implicated in the transcriptional activation of several viruses, including HIV-1 (Nabel et al., Nature 326:711 (1987); Kaufman et al., Mol. Cell. Biol., 7:3759 (1987)). The various signaling pathways that can control the activation of NF-xcexaB are not all clearly understood. It is apparent that different inducers can initiate their pathways through distinct receptors.
The latent cytoplasmic form of NF-xcexaB is associated with a cytoplasmic inhibitory protein called IxcexaB. Baeuerle and Baltimore, Science 242:540 (1988); PCT US92/04073 (WO 92/20795). The release of NF-xcexaB from IxcexaB results in the rapid appearance of the active form of NF-xcexaB in the cell nucleus. Genes regulated by NF-xcexaB can be transcriptionally activated minutes after exposure of the cell to the appropriate inducer. Activation of NF-xcexaB after exposure of a cell to an inducer is correlated with the hyperphosphorylation of IxcexaBxcex1 and its subsequent degradation. As IxcexaB is diminished in the cytoplasm, NF-xcexaB increases in the nucleus. Phosphorylation of IxcexaB was once thought to lead to dissociation from NF-xcexaB and subsequent proteolysis of IxcexaB. Beg and Baldwin, Genes Dev. 7:2064 (1993). More recently, it has been proposed that the proteasome is responsible for signal-mediated degradation of IxcexaBxcex1 and IxcexaBxcex2. Baldwin, Annu. Rev. Immunol. 14:649 (1996). Phosphorylation of IxcexaB apparently renders the molecule susceptible to proteolysis.
Activation of NF-xcexaB has been suggested as playing a pathological role in the development of autoimmune diseases and chronic inflammatory diseases such as rheumatoid arthritis, and in acute situations such as septic shock.
A first aspect of the present invention is a method of enhancing the cytotoxic effects of an antineoplastic chemotherapeutic agent. A therapeutically effective amount of NF-xcexaB inhibitor is administered in conjunction with the chemotherapeutic agent, so that the cytotoxic effect of the chemotherapeutic agent is increased compared to that which occurs in the absence of NF-xcexaB inhibitor.
A further aspect of the present invention is a method of enhancing chemotherapeutic cytotoxicity in a subject treated with a chemotherapeutic agent. A therapeutically effective amount of NF-xcexaB inhibitor is administered to a subject in conjunction with a chemotherapeutic agent. The cytotoxic effect of the chemotherapeutic agent is increased compared to that which occurs in the absence of NF-xcexaB inhibitor.
A further aspect of the present invention is a method of enhancing the cytotoxic effect of TNFxcex1, by administering a therapeutically effective amount of NF-xcexaB inhibitor in conjunction with TNFxcex1. The cytotoxic effect of TNFxcex1 is increased compared to that which occurs in the absence of NF-xcexaB inhibitor.
A further aspect of the present invention is a method of enhancing chemotherapeutic cytotoxicity in a subject treated with TNFxcex1, by administering a therapeutically effective amount of NF-xcexaB inhibitor in conjunction with TNFxcex1. The cytotoxic effect of TNFxcex1 is increased compared to that which occurs in the absence of NF-xcexaB inhibitor.
A further aspect of the present invention is a method of screening a compound for the ability to reduce the anti-apoptotic protective effects of an NF-xcexaB induced anti-apoptotic gene. A population of test cells is exposed to an anticancer treatment and a test compound, and the cell viability following the exposure is assessed. Reduced cell viability, compared to that which occurs in cells treated only with the anticancer treatment, indicates that the test compound reduces the anti-apoptotic effects of an NF-xcexaB induced anti-apoptotic gene.
The foregoing and other objects and aspects of the present invention are explained in detail in the specification set forth below.